Hej, Rüdiger!
Thanks for your input!
No one else on this list seem to bother...but strangly there are people that got sound on 12.04, but perhaps it is broken on 13.10?
Anyway, I upgraded to 14.04 now, and I will run som more tests, both with fat clients, and with thin clients with local apps.
Do you run just thin clients(with local apps), or do you have the same experience with fat clients?
Which version are you running?
I try to confirm your tests/theories, and get back to you, but I don't have much time right now...
Strange that I haven't heard anything about this before, it SHOULD be a big issue in the edubuntu community, as far as I could imagine...?
Best regards from/Med vänliga hälsningar från
Johan Kragsterman
Capvert
-----Rüdiger Kupper <k...@kg-fds.de> skrev: -----
Till: ltsp-discuss@lists.sourceforge.net
Från: Rüdiger Kupper <k...@kg-fds.de>
Datum: 2014-04-22 10:03
Ärende: Re: [Ltsp-discuss] Ang: no sound on fat clients
Från: Rüdiger Kupper <k...@kg-fds.de>
Datum: 2014-04-22 10:03
Ärende: Re: [Ltsp-discuss] Ang: no sound on fat clients
Hello Johan,
I believe I see the same problem on our thin clients, and I have a
theory what makes the sound break. I believe that the problem is related
to the sample rate of the sound you try to play.
Regarding your experiments with a DVB stream and youtube, I'd expect
that the DVB stream comes with 48 kHz audio sampling rate, while the
youtube video had 44.1 kHz?
I can completely reproduce your results with two sample audio files, one
with 44.1 kHz and one with 48 kHz sample rate. Here is what I see:
Test1:
- I boot up the thin client and open the 44.1 kHz file, it works.
Test 2:
- I boot up the thin client and open the 48 kHz file. From what the
player shows, it appears to play, but I have no sound.
- I close that file and open the 44.1 kHz file (the one that worked fine
in test 1), and have no sound either.
- Sound will not come back until I reboot the client.
Test 3:
- I boot up the thin client and open the 44.1 kHz file. I have sound.
- I keep this file playing (endless loop). In parallel I open the 48 kHz
file. I have sound, both files play together.
In short, my theory is that 48 kHz playback breaks pulseaudio on LTSP
clients.
So why does test 3 work? When you first play a 44.1 kHz audio stream and
in parallel open a 48 kHz stream, I believe pulseaudio will sample down
the second stream to 44.1 kHz to mix it into the already playing stream.
That's why audio works in test 3, and that also constitutes a workaround.
Workaround: Tell your users to open up a 44.1 kHz youtube video, start
to play and pause it, keep the browser window open. After that sound
will work and stay up, no matter what file they play.
This is really just a workaround, but our users were very thankful
having it (we use LTSP in classrooms, and the difference of having or
not having sound can well break or make a teacher's complete lesson...)
In any case, it would be much better to really fix the problem.
So, Johan, I'd ask you to confirm my three test cases above. I can
supply two sample mp3 files if you need, please give me a note. It will
be no difference what software you use for playback, as long as it uses
pulseaudio (VLC is fine).
If you confirm the test, we need some pulseaudio or LTSP developer to
(a) find the reason, and/or (b) tell us if pulseaudio can be set up to
generally downsample all audio to 44.1 kHz on our clients.
Looking forward to seeing your results,
best regards,
Rüdiger
On 13.04.2014 07:37, Johan Kragsterman wrote:
> The results are strange....
>
> If I start with VLC, directly after the newly booted client, and ltsp-localapps pulseaudio -nC:
>
> ltsp-localapps vlc:
>
> VLC recieving dvb streams from my TV-server(mumudvb) doesn't play any sound, though it displays that sound is in the stream, and it lets me choose the local sound device to use(Just a note: This works perfect on a normal workstation).
>
> If I start with google-chrome, and youtube, directly after the newly booted client, and ltsp-localapps pulseaudio -nC:
>
> It seem to work fine with the sound, though the video quality is not fine.
>
> If I start VLC AFTER I started google-chrome/youtube where the sound is already working, sound is actually working on vlc as well, though NOT in all channels...!?!!?
> So, I don't really know what I'm doing here, just doing experiments, and reports back to list.
>
> But any hints here would be appreciated, and a strategy for solving this would be fine!
--
Dr. Rüdiger Kupper <k...@kg-fds.de>
Kepler-Gymnasium Freudenstadt
I believe I see the same problem on our thin clients, and I have a
theory what makes the sound break. I believe that the problem is related
to the sample rate of the sound you try to play.
Regarding your experiments with a DVB stream and youtube, I'd expect
that the DVB stream comes with 48 kHz audio sampling rate, while the
youtube video had 44.1 kHz?
I can completely reproduce your results with two sample audio files, one
with 44.1 kHz and one with 48 kHz sample rate. Here is what I see:
Test1:
- I boot up the thin client and open the 44.1 kHz file, it works.
Test 2:
- I boot up the thin client and open the 48 kHz file. From what the
player shows, it appears to play, but I have no sound.
- I close that file and open the 44.1 kHz file (the one that worked fine
in test 1), and have no sound either.
- Sound will not come back until I reboot the client.
Test 3:
- I boot up the thin client and open the 44.1 kHz file. I have sound.
- I keep this file playing (endless loop). In parallel I open the 48 kHz
file. I have sound, both files play together.
In short, my theory is that 48 kHz playback breaks pulseaudio on LTSP
clients.
So why does test 3 work? When you first play a 44.1 kHz audio stream and
in parallel open a 48 kHz stream, I believe pulseaudio will sample down
the second stream to 44.1 kHz to mix it into the already playing stream.
That's why audio works in test 3, and that also constitutes a workaround.
Workaround: Tell your users to open up a 44.1 kHz youtube video, start
to play and pause it, keep the browser window open. After that sound
will work and stay up, no matter what file they play.
This is really just a workaround, but our users were very thankful
having it (we use LTSP in classrooms, and the difference of having or
not having sound can well break or make a teacher's complete lesson...)
In any case, it would be much better to really fix the problem.
So, Johan, I'd ask you to confirm my three test cases above. I can
supply two sample mp3 files if you need, please give me a note. It will
be no difference what software you use for playback, as long as it uses
pulseaudio (VLC is fine).
If you confirm the test, we need some pulseaudio or LTSP developer to
(a) find the reason, and/or (b) tell us if pulseaudio can be set up to
generally downsample all audio to 44.1 kHz on our clients.
Looking forward to seeing your results,
best regards,
Rüdiger
On 13.04.2014 07:37, Johan Kragsterman wrote:
> The results are strange....
>
> If I start with VLC, directly after the newly booted client, and ltsp-localapps pulseaudio -nC:
>
> ltsp-localapps vlc:
>
> VLC recieving dvb streams from my TV-server(mumudvb) doesn't play any sound, though it displays that sound is in the stream, and it lets me choose the local sound device to use(Just a note: This works perfect on a normal workstation).
>
> If I start with google-chrome, and youtube, directly after the newly booted client, and ltsp-localapps pulseaudio -nC:
>
> It seem to work fine with the sound, though the video quality is not fine.
>
> If I start VLC AFTER I started google-chrome/youtube where the sound is already working, sound is actually working on vlc as well, though NOT in all channels...!?!!?
> So, I don't really know what I'm doing here, just doing experiments, and reports back to list.
>
> But any hints here would be appreciated, and a strategy for solving this would be fine!
--
Dr. Rüdiger Kupper <k...@kg-fds.de>
Kepler-Gymnasium Freudenstadt
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Get Started Now And Turn Your Intranet Into A Collaboration Platform
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For additional LTSP help, try #ltsp channel on irc.freenode.net
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_____________________________________________________________________
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